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Anonymous Poster #1

How to Control Flatness in Punching Perforated Part

10/05/2015 4:07 AM

Hi Guys

I am facing a problem on controlling material flatness of a sheet metal plate. (Al5052 h32 thk 1.60mm). Refer figure below for detail of the part. the flatness need to be control is 0.50mm. (machine used is trumpf CNC punching machine 6000L).

Any one had idea or experience in controlling this flatness.

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#1

Re: how to control flatness in punching perforated part.

10/05/2015 6:22 AM

I know nothing about this sort of thing, but, just an idea:-

Could you punch every other hole from one side of the plate then turn it over and do the other half of the holes.

I appreciate that it would be a lot easier if the holes were on a square grid: then you could do a chequerboard on one side then turn it over to do the reverse chequerboard. With the triangular/hexagonal grid you are still going to end up with "ripples".

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#2

Re: How To Control Flatness In Punching Perforated Part.

10/05/2015 8:36 AM

Ask you cnc rep about setting up for fineblanking.

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#12
In reply to #2

Re: How To Control Flatness In Punching Perforated Part.

10/07/2015 3:18 PM

It is worth reiterating, since it has not received much discussion; fineblanking is the best way to do this unless you are going to change to something laser or waterjet.

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#3

Re: How To Control Flatness In Punching Perforated Part.

10/05/2015 9:04 AM

Your CNC does not have that feature? It should worth to double check, call your cnc provider for technical support.

If it's not too costly for you, you might call your local automation service provider. Laser positioning could be integrated on your cnc with no problem.

Above picture is a laser sensor made in Germany, you may find similar item through our list of suppliers here in IHS.

Oops, you said 0.5mm right.?

Capacitive sensors could be employed

Sensing capability - 0.1 to 1.5 mm, hope that helps.

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#6
In reply to #3

Re: How To Control Flatness In Punching Perforated Part.

10/05/2015 2:38 PM

This is a good way of detecting the feature, but the OP's problem is Controlling it.

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#4

Re: How To Control Flatness In Punching Perforated Part.

10/05/2015 9:55 AM

This may require a secondary operation to achieve the flatness requirement.

Running it through a two roller flattening machine may be needed.

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#13
In reply to #4

Re: How To Control Flatness In Punching Perforated Part.

10/08/2015 12:02 AM

Don't you mean primary roller operation then punching to happen?

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#14
In reply to #13

Re: How To Control Flatness In Punching Perforated Part.

10/08/2015 7:13 AM

That order is unlikely to improve the distortion introduced by punching.

...that is, assuming we are still using the customary direction of time. Moreover, in the time reversed perspective, the cnc unpuncher is doing a fine job of undistorting the sheets as it fills all the holes with just the right pieces...seamlessly.

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#5

Re: How To Control Flatness In Punching Perforated Part.

10/05/2015 2:35 PM

A few questions:

How many holes is the machine set up to punch at one time?

Is the die-to-punch clearance correct?

Are you able to adjust punch speed?

Are the tools made to the correct specifications? Are they coated? Are they worn out?

Are you using a lubricant?

Are you pulling excessive burrs in the holes?

What flatness are you able to obtain with this setup (how bad is bad)?

Is this a part that started off well, and control has degraded, or is this something new that someone in sales sold and now you are stuck with it?

It seems that there is very little "web" left to maintain rigidity in the sheet after all those intricate holes are punched.

I'm sure there are more variables to consider if I had time to think of them all.

Short of that, I agree with Lyn that a secondary rolling/flattening process should be considered.

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#7

Re: How To Control Flatness In Punching Perforated Part.

10/05/2015 3:11 PM

Punch and die condition? Clearance? Factors that would cause the sheet to bend.

.5mm(20 thousands of an inch) tolerance on flatness on the sheet. Are the specs on the raw materials to that? Specs on aluminum sheet of that thickness to 36" wide is 9/16". So is the problem the process or the raw material?

As others have mention rolling it flat after the punching.

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#8

Re: How to Control Flatness in Punching Perforated Part

10/06/2015 6:24 AM
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#15
In reply to #8

Re: How to Control Flatness in Punching Perforated Part

10/08/2015 9:29 PM

Thanks Bro, This really help. Let me try on this type of tool and updateds you guys on the latest results.thanks a lot for the info provide.

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#9

Re: How to Control Flatness in Punching Perforated Part

10/06/2015 9:38 AM

Use a laser to cut the holes

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#10

Re: How to Control Flatness in Punching Perforated Part

10/06/2015 10:21 AM

You should establish an account where your name appears.

We manufacture a machine called a Hydrocooler, that is used for processing cherries, so we do use perforated sheetmetal for the job. Perforated sheetmetal with specific hole size and spacing is needed to control the amound of water saturation on the cherries. Normally we can order perforated sheetmetal from vendors to specification. If none is available, we have it laser cut. If the holes are too close together that the heat will cause wargage then have it waterjet. Are the holes required to be that large and that close? You can get expanded metal that is flat that is 1/2-13.

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#11

Re: How to Control Flatness in Punching Perforated Part

10/07/2015 8:56 AM

You may want to try something like This,

Not an endorsement,

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